Open Shortest Path First Extensions in Support of Wavelength Switched Optical Networks

ABSTRACT

A network component comprising a generalized multiprotocol label switching (GMPLS) control plane controller configured to implement a method comprising transmitting a message to at least one adjacent control plane controller, wherein the message comprises a Type-Length-Value (TLV) indicating Routing and Wavelength Assignment (RWA) information, wherein the TLV comprises a Node Attribute TLV, a Link Set TLV, or both, and wherein the TLV further comprises at least one sub-TLV indicating additional RWA information. A method comprising communicating an open shortest path first (OSPF) link state advertisement (LSA) message comprising a TLV with at least one sub-TLV to a GMPLS control plane controller, wherein the TLV comprises a Node Attribute TLV, a Link Set TLV, or both, and wherein the TLV further comprises at least one sub-TLV indicating RWA information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/557,978 filed on Dec. 2, 2014 by Greg Bernsteinand Young Lee and titled “Open Shortest Path First Extensions in Supportof Wavelength Switched Optical Networks,” which is a continuation ofU.S. Pat. No. 8,929,733 issued Jan. 6, 2015 and titled “Open ShortestPath First Extensions in Support of Wavelength Switched OpticalNetworks,” which is a continuation of U.S. Pat. No. 8,374,502 issuedFeb. 12, 2013 and titled “Open Shortest Path First Extensions in Supportof Wavelength Switched Optical Networks,” which claims priority to U.S.provisional patent application No. 61/156,285 filed Feb. 27, 2009 byGreg Bernstein and Young Lee and titled “Open Shortest Path FirstExtensions in Support of Wavelength Switched Optical Networks,” all ofwhich are incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

Wavelength division multiplexing (WDM) is one technology that isenvisioned to increase bandwidth capability and enable bidirectionalcommunications in optical networks. In WDM networks, multiple datasignals can be transmitted simultaneously between network elements (NEs)using a single fiber. Specifically, the individual signals may beassigned different transmission wavelengths so that they do notinterfere or collide with each other. The path that the signal takesthrough the network is referred to as the lightpath. One type of WDMnetwork, a wavelength switched optical network (WSON), seeks to switchthe optical signals with fewer optical-electrical-optical (0E0)conversions along the lightpath, e.g. at the individual NEs, thanexisting optical networks.

One of the challenges in implementing WDM networks is the determinationof the routing and wavelength assignment (RWA) for the various signalsthat are being transported through the network at any given time. Tocomplete the RWA process, sufficient information must be provided tothis process to insure its successful completion. As such, the RWAcontinues to be one of the challenges in implementing WDM technology inoptical networks.

SUMMARY

In one embodiment, the disclosure includes a network componentcomprising a generalized multiprotocol label switching (GMPLS) controlplane controller configured to implement a method comprisingtransmitting a message to at least one adjacent control planecontroller, wherein the message comprises a Type-Length-Value (TLV)indicating RWA information, wherein the TLV comprises a Node AttributeTLV, a Link Set TLV, or both, and wherein the TLV further comprises atleast one sub-TLV indicating additional RWA information.

In another embodiment, the disclosure includes a method comprisingcommunicating an open shortest path first (OSPF) link stateadvertisement (LSA) message comprising a TLV with at least one sub-TLVto a GMPLS control plane controller, wherein the TLV comprises a NodeAttribute TLV, a Link Set TLV, or both, and wherein the TLV furthercomprises at least one sub-TLV indicating RWA information.

In yet another embodiment, the disclosure includes an apparatuscomprising a GMPLS control plane controller configured to communicate aLSA comprising a TLV to at least one adjacent control plane controller,wherein the TLV comprises a Node Attribute TLV, a Link Set TLV, or both,and wherein the TLV further comprises at least one sub-TLV with RWAinformation.

These and other features will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a schematic diagram of an embodiment of a WSON system.

FIG. 2 is a schematic diagram of an embodiment of a path computationelement (PCE) architecture.

FIG. 3 is a schematic diagram of another embodiment of the PCEarchitecture.

FIG. 4 is a schematic diagram of another embodiment of the PCEarchitecture.

FIG. 5 is a protocol diagram of an embodiment of the communicationsbetween a NE, a first control plane controller, and a second controlplane controller.

FIG. 6 is a schematic diagram of an embodiment of a Node Attribute TLVwith shared risk node group sub-TLV values.

FIG. 7 is a schematic diagram of an embodiment of a connectivity matrixsub-TLV.

FIG. 8 is a schematic diagram of an embodiment of a Link Set object.

FIG. 9 is a schematic diagram of an embodiment of a port wavelengthrestrictions sub-TLV.

FIG. 10 is a schematic diagram of an embodiment of a wavelengthavailability sub-TLV.

FIG. 11 is a schematic diagram of an embodiment of a general-purpose ofcomputer system.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

In WSONs where there are no, or a limited number of, switches capable ofwavelength conversion, paths must be set up subject to the “wavelengthcontinuity” constraint. This leads to a path computation problem knownas RWA. In order to perform such computations, it is necessary tocollect information about the available wavelengths within the network.A framework exists for applying GMPLS and the PCE architecture tocontrol WSONs to address the RWA problem. An existing information modelspecifies the information needed at various points in a WSON in order tocompute paths and establish Label Switched Paths (LSPs). Based on theinformation model, efficient protocol-independent encodings of theinformation needed by the RWA process in a WSON can be provided. Suchencodings can be used to extend GMPLS signaling and routing protocols.

In order to enable GMPLS to support RWA in WSONs networks, extensions tothe OSPF routing protocol are disclosed herein to enhance the definedTraffic Engineering (TE) properties of GMPLS TE. The enhancements to theTE properties of GMPLS TE links can be announced in OSPF TE LSAs. The TELSA, which is an opaque LSA with area flooding scope, has only onetop-level TLV triplet and has one or more nested sub-TLVs forextensibility. The top-level TLV can take one of three values: (1)Router Address; (2) Link; and (3) Node Attribute. In accordance with atleast some embodiments, sub-TLVs for the Link TLV and Node Attribute TLVare enhanced in support of RWA in a WSON under the control of GMPLS.

Disclosed herein is a system and method that compactly encodesinformation needed for RWA in WDM networks, such as the WSON.Specifically, a control plane controller may send a message to at leastone adjacent control plane controller, where the message comprises theRWA information in the form of at least one enhanced TLV or sub-TLV. Inat least some embodiments, the enhanced sub-TLV information providesshared risk node group (SRNG) information, connectivity matrixinformation, wavelength converter pool information (e.g., wavelengthconverter accessibility information, wavelength conversion rangeinformation, and wavelength converter (WC) usage state information),WSON port wavelength restrictions information, available wavelengthsinformation, and shared backup wavelengths information. In at least someembodiments, a Node Attribute TLV and/or a Link TLV includes one or moreof the enhanced sub-TLVs described herein. The length of these sub-TLVsmay vary.

In WSON networks, generally all the sub-TLVs above are optional,depending on the implementation. For example, a connectivity matrixsub-TLV may appear in the LSAs because WSON switches are presentlyasymmetric. If there is no connectivity matrix sub-TLV in the LSAs, itis assumed that the switches are symmetrically switching. If there iswavelength conversion functionality in the WSON networks, thenwavelength converter accessibility sub-TLVs, wavelength conversion rangesub-TLVs, and/or WC usage state sub-TLVs should appear in the LSAs.

FIG. 1 illustrates one embodiment of a WSON system 100. In accordancewith embodiments, various sub-TLVs for Link TLVs and/or Node AttributeTLVs are enhanced in support of RWA for the WSON 100 under the controlof GMPLS. As shown, the system 100 may comprise an optical transportplane 110 comprising a plurality of NEs 112, a control plane 114comprising a plurality of control plane controllers 120, and a PCE 130.The NEs 112, control plane controllers 120, and PCE 130 may communicatewith each other via optical, electrical, or wireless means. In anembodiment, the NEs 112 may be coupled to one another using opticalfibers. Similarly, the control plane controllers 120 may be coupled toone another using optical fibers, perhaps the same optical fibers usedto connect the NEs 112. In some cases, these optical fibers may also beconsidered NEs 112. A plurality of optical signals may be transportedthrough the optical transport plane 110 over lightpaths that may passthrough some of the NEs 112. In addition, at least some of the NEs 112,for example those at the ends of the optical transport plane 110, may beconfigured to convert between electrical signals from external sources,e.g. core network and/or user network interface (UNI) data, and theoptical signals used in the optical transport plane 110. Similarly, atleast some of the control plane controllers 120, for example those atthe ends of the control plane 114, may be configured to convert betweenelectrical signals from external sources, e.g. UNI control and/ornetwork management interface (NMI) signals, and the optical signals usedin the control plane 114. Although four NEs 112, four control planecontrollers 120, and one PCE 130 are shown in the system 100, the system100 may comprise any number of NEs 112, control plane controllers 120,or PCEs 130. Moreover, while a one-to-one relationship between thecontrol plane controllers 120 and the NEs 112 is illustrated in FIG. 1,there may be many NEs 112 associated with a single control planecontroller 120, or vice-versa. Similarly, while the control planecontrollers 120 are associated with a single PCE 130 in FIG. 1, theremay be many PCEs 130 in the system 100, and the control planecontrollers 120 may be associated with one or more of the PCEs 130 orvice-versa.

The optical transport plane 110 may be part of the system 100 that usesactive or passive components to transport optical signals. The opticaltransport plane 110 may implement WDM to transport the optical signalsthrough the optical transport plane 110, and may comprise variousoptical components as described in detail below. The optical transportplane 110 may be part of a long haul network, a metropolitan network, ora residential access network.

The NEs 112, also referred to as nodes, may be any devices or componentsthat transport signals through the optical transport plane 110. In anembodiment, the NEs 112 consist essentially of optical processingcomponents, such as line ports, add ports, drop ports, transmitters,receivers, amplifiers, optical taps, and so forth, and do not compriseany electrical processing components. Alternatively, the NEs 112 maycomprise a combination of optical processing components and electricalprocessing components. At least some of the NEs 112 may be configuredwith wavelength converters, optical-electrical (OE) converters,electrical-optical (EO) converters, 0E0 converters, or combinationsthereof. However, it may be advantageous for at least some of the NEs112 to lack such converters as such may reduce the cost and complexityof the system 100. In specific embodiments, the NEs 112 may compriseoptical cross connects (OXCs), photonic cross connects (PXCs), type I ortype II reconfigurable optical add/drop multiplexers (ROADMs),wavelength selective switches (WSSs), fixed optical add/dropmultiplexers (FOADMs), or combinations thereof.

The NEs 112 may be coupled to each other via optical fibers, alsoreferred to as links. The optical fibers may be used to establishoptical links and transport the optical signals between the NEs 112. Theoptical fibers may comprise standard single mode fibers (SMFs) asdefined in International Telecommunication Union (ITU) TelecommunicationStandardization Section (ITU-T) standard G.652, dispersion shifted SMFsas defined in ITU-T standard G.653, cut-off shifted SMFs as defined inITU-T standard G.654, non-zero dispersion shifted SMFs as defined inITU-T standard G.655, wideband non-zero dispersion shifted SMFs asdefined in ITU-T standard G.656, or combinations thereof. These fibertypes may be differentiated by their optical impairment characteristics,such as attenuation, chromatic dispersion, polarization mode dispersion(PMD), four wave mixing, or combinations thereof. These effects may bedependent upon wavelength, channel spacing, input power level, orcombinations thereof. The optical fibers may be used to transport WDMsignals, such as course WDM (CWDM) signals as defined in ITU-T G.694.2or dense WDM (DWDM) signals as defined in ITU-T G.694.1. All of thestandards described herein are incorporated herein by reference.

The control plane 114 may be any part of the system 100 that handlesoperation, administration, and maintenance (OAM), control messages,and/or general administration of the system 100. The control plane 114may use the optical transport plane 110 to exchange messages, or mayhave its own message distribution network. The control plane 114 maycomprise various control plane controllers 120 as described in detailbelow.

The control plane controllers 120, also called optical connectioncontrollers, may coordinate activities between the NEs 112.Specifically, the control plane controllers 120 may receive opticalconnection requests and provide lightpath signaling to the NEs 112 via aconnection control interface (CCI), thereby coordinating the NEs 112such that data signals are routed through the optical transport plane110 with little or no contention. The control plane controllers 120 maycommunicate with each other using any suitable protocol, such as GMPLSor an Interior Gateway Protocol (IGP). In addition, the control planecontrollers 120 may communicate with the PCE 130 using PCE protocol(PCEP) to provide the PCE 130 with information that may be used for theRWA, receive the RWA from the PCE 130, and/or forward the RWA to the NEs112. The control plane controllers 120 may be located in a componentoutside of the NEs 112, such as an external server, or may be part ofthe NEs 112. In an embodiment, the control plane controllers 120 cancompute the Routing Assignment (RA), the Wavelength Assignment (WA), orboth.

The PCE 130 may perform all or part of the RWA for the WSON system 100.Specifically, the PCE 130 may receive the wavelength or otherinformation that may be used for the RWA from the control planecontrollers 120, from the NEs 112, or both. The PCE 130 may process theinformation to obtain the RWA, for example, by computing the routes,e.g. lightpaths, for the optical signals, specifying the opticalwavelengths that are used for each lightpath, and determining the NEs112 along the lightpath at which the optical signal should be convertedto an electrical signal or a different wavelength. The RWA may includeat least one route for each incoming signal and at least one wavelengthassociated with each route. The PCE 130 may then send all or part of theRWA information to the control plane controller 120 or directly to theNEs 112. To assist the PCE 130 in this process, the PCE 130 may compriseor interface with a global traffic-engineering database (TED) 132, a RWAinformation database 136, an optical performance monitor (OPM) 134, aphysical layer constraint (PLC) information database (not shown), orcombinations thereof. The PCE 130 may be located in a component outsideof the system 100, such as an external server, or may be located in acomponent within the system 100, such as a control plane controller 120or a NE 112.

In some embodiments, the RWA information may be sent to the PCE 130 by aPath Computation Client (PCC). The PCC may be any client applicationrequesting a path computation to be performed by the PCE 130. The PCCmay also be any network component that makes such a request, such as thecontrol plane controller 120, or any NE 112, such as a ROADM or a FOADM.

The PCE 130 may be embodied in one of several architectures. FIG. 2illustrates an embodiment of a combined RWA architecture 200. In thecombined RWA architecture 200, the PCC 210 communicates the RWA requestand the required information to the PCE 220, which implements both therouting assignment and the wavelength assignment functions using asingle computation entity, such as a processor. For example, theprocessor may process the RWA information using a single or multiplealgorithms to compute the lightpaths as well as to assign the opticalwavelengths for each lightpath. The amount of RWA information needed bythe PCE 220 to compute the RWA may vary depending on the algorithm used.If desired, the PCE 220 may not compute the RWA until sufficient networklinks are established between the NEs or when sufficient RWA informationabout the NEs and the network topology is provided. The combined RWAarchitecture 200 may be preferable for network optimization, smallerWSONs, or both.

FIG. 3 illustrates an embodiment of a separated RWA architecture 300. Inthe separated RWA architecture 300, the PCC 310 communicates the RWArequest and the required information to the PCE 320, which implementsboth the routing function and the wavelength assignment function usingseparate computation entities, such as processors 322 and 324.Alternatively, the separated RWA architecture 300 may comprise twoseparate PCEs 320 each comprising one of the processors 322 and 324.Implementing routing assignment and wavelength assignment separately mayoffload some of the computational burden on the processors 322 and 324and reduce the processing time. In an embodiment, the PCC 310 may beaware of the presence of only one of two processors 322, 324 (or twoPCEs) and may only communicate with that processor 322, 324 (or PCE).For example, the PCC 310 may send the RWA information to the processor322, which may compute the lightpath routes and forward the routingassignment to the processor 324 where the wavelength assignments areperformed. The RWA may then be passed back to the processor 322 and thento the PCC 310. Such an embodiment may also be reversed such that thePCC 310 communicates with the processor 324 instead of the processor322.

In either architecture 200 or 300, the PCC 210 or 310 may receive aroute from the source to destination along with the wavelengths, e.g.GMPLS generalized labels, to be used along portions of the path. TheGMPLS signaling supports an explicit route object (ERO). Within an ERO,an ERO label sub-object can be used to indicate the wavelength to beused at a particular NE. In cases where the local label map approach isused, the label sub-object entry in the ERO may have to be translated.

FIG. 4 illustrates a distributed wavelength assignment architecture 400.In the distributed wavelength assignment architecture 400, the PCE 410may receive some or all of the RWA information from the NEs 420, 430,and 440, perhaps via direct link, and implements the routing assignment.The PCE 410 then directly or indirectly passes the routing assignment tothe individual NEs 420, 430, and 440, which assign the wavelengths atthe local links between the NEs 420, 430, and 440 based on localinformation. Specifically, the NE 420 may receive local RWA informationfrom the NEs 430 and 440 and send some or all of the RWA information tothe PCE 410. The PCE 410 may compute the lightpaths using the receivedRWA information and send the list of lightpaths to the NE 420. The NE420 may use the list of lightpaths to identify the NE 430 as the next NEin the lightpath. The NE 420 may establish a link to the NE 430 and usethe received local RWA information that may comprise additionalconstraints to assign a wavelength for transmission over the link. TheNE 430 may receive the list of lightpaths from the NE 420, use the listof lightpaths to identify the NE 440 as the next NE in the lightpath,establish a link to the NE 440, and assign the same or a differentwavelength for transmission over the link. Thus, the signals may berouted and the wavelengths may be assigned in a distributed mannerbetween the remaining NEs in the network. Assigning the wavelengths atthe individual NEs may reduce the amount of RWA information that has tobe sent to the PCE 410.

FIG. 5 illustrates an embodiment of a communication method 500 between aNE, a first control plane controller, and a second control planecontroller, which may be an adjacent control plane controller. In someembodiments, the method 500 may occur between a NE, a first controlplane controller, and the PCE, for example, when the first control planecontroller sends the RWA information to the TED in the PCE. In themethod 500, the first control plane controller obtains the RWAinformation 502 from at least one NE. The NE may send the RWAinformation 502 to the first control plane controller without promptingby the first control plane controller, or the NE may send the RWAinformation 502 to the first control plane controller in response to arequest by the first control plane controller. The first control planecontroller then sends a message 504 to the second control planecontroller, where the message 504 comprises at least one of the RWAinformation described below. Specifically, the RWA information may beembodied in at least one Link TLV and/or Node Attribute TLV with one ofmore of the enhanced sub-TLVs described herein. As used herein, the termTLV may refer to any data structure that carries the RWA information.The message 504 and perhaps the TLV may also comprise a status indicatorthat indicates whether the RWA information is static or dynamic. In anembodiment, the status indicator may indicate how long the static ordynamic status lasts, so that the second control plane controller canknow how long the RWA information is valid and/or when to expect anupdate. Additionally or alternatively, the message 504 and perhaps theTLV may comprise a type indicator that indicates whether the RWAinformation is associated with a node, a link, or both.

One of the enhanced sub-TLVs disclosed herein is for SRNG values. FIG. 6is a schematic diagram of an embodiment of an enhanced Node AttributeTLV 600 that comprises a predetermined Node Attribute TLV 602 with SRNGsub-TLV values 604A-604N. In at least some embodiments, the length ofeach SRNG value is the length of the list in octets. As an example, theSRNG values 604A-604N may comprise an unordered list of 32-bit numbers.The SRNG values 604A-604N may be similar to the SRNGs defined inInternet Engineering Task Force (IETF) documentdraft-ietf-ccamp-rwa-info-01.txt, which is incorporated herein byreference.

Another enhanced sub-TLV disclosed herein is for connectivity matrixvalues. FIG. 7 is a schematic diagram of an embodiment of a connectivitymatrix sub-TLV 700. In accordance with at least some embodiments, theconnectivity matrix sub-TLV 700 is a sub-TLV of a Node Attribute TLV. Asshown, the sub-TLV 700 comprises a connectivity field 702, a reservedfield 704, Link Set A values 706, and Link Set B values 708. The sub-TLV700 may further comprise additional Link Set pair values 710 as neededto specify connectivity. In accordance with at least some embodiments,the connectivity matrix sub-TLV 700 identifies which ingress ports andwavelengths can be connected to a specific egress port. The connectivitymatrix sub-TLV 700 may identify either the potential connectivity matrixfor asymmetric switches (e.g., ROADMs and such) or fixed connectivityfor an asymmetric device such as a multiplexer. In either case, theinformation is useful because the switching devices in a WSON are highlyasymmetric. In accordance with embodiments, one sub-TLV 700 contains onematrix. Further, the connectivity matrix sub-TLV 700 may occur more thanonce such that multi-matrices are provided within the same NodeAttribute TLV.

In at least some embodiments, the connectivity field 702 may comprisethe first about seven bits of the sub-TLV 700, and may indicate thereconfigurability of a network element. For example, the connectivityfield 702 may be set to “0” when the network element is fixed. In suchcase, the connectivity matrix sub-TLV 700 represents the potentialconnectivity matrix of asymmetric fixed deices or the fixed part of a“hybrid” device. Additionally, the connectivity field 702 may be set to“1” when the network element is reconfigurable, as is the case with aROADM or OXC. In such case, the connectivity matrix sub-TLV 700represents the potential connectivity matrix for asymmetric switches.

The reserved field 704 may be the subsequent about 24 bits of thesub-TLV 700, and may be used for other purposes. In at least someembodiments, the reserved field bits are set to zero upon transmissionand/or are ignored upon reception. The Link Set A 706 may be variable inlength and may specify the ingress links for the node. The Link Set B708 may be variable in length and may specify the egress links for thenode. The additional Link Sets 710 may be variable in length and mayspecify any additional links. In at least some embodiments, the order ofthe Link Set A 706, the Link Set B 708, and the additional Link Sets 710is unimportant (e.g., the Link Sets 706, 708 and 710 may be arranged inany order).

The connectivity matrix sub-TLV 700 may be better understood by applyingit to a two-degree, 40-channel ROADM as an example. The ROADM may haveone line side ingress port, one line side egress port, 40 add ports, and40 drop ports. The ports may be numbered and identified according to thelink to which they are connected, such that the line side ingress portcan be identified by link local identifier #1, the 40 add ports can beidentified by link local identifiers #2-#41, the egress line side portcan be identified by link local identifier #42, and the 40 drop portscan be identified by link local identifiers #43-#82. Within the ROADM,the line side ingress port may be connected to the line side egress portand to all of the drop ports. Similarly, the add ports may be connectedto the line side egress port, but not any of the drop ports.

In at least some embodiments, a connectivity matrix sub-TLV 700 includesa Link Set object. FIG. 8 is a schematic diagram of an embodiment ofsuch a Link Set object 800. As shown, the Link Set object 800 comprisesan action field 802, a directionality (“Dir”) field 804, a format field806, and a reserved field 808. Further, the Link Set object 800comprises a plurality of link identifiers 810.

In at least some embodiments, the action field 802 comprises around 8bits with select values being defined (e.g., as flag values) and othervalues being reserved. For example, a value 0x01 may indicate aninclusive list where one or more link elements are included in the LinkSet. Meanwhile, a value 0x02 may indicate an inclusive range of links,where two elements define the range (e.g., the first element indicatesthe start of the range and the second element indicates the end of therange). A value of “0” indicates that there is no bound on thecorresponding portion of the range. The directionality field 804comprises, for example, two bits to indicate a Link Set directionality.For example, a value of 0x01 indicates a bidirectional Link Set, and avalue of 0x02 indicates links in the Link Set are from the incomingdirection. Meanwhile, a value of 0x03 indicates links in the Link Setare to the outgoing direction.

The format field 806 comprises, for example, 6-bits to indicate theformat of the link identifier. In an embodiment, a value of 0x01indicates that the links in the Link Set are identified by the linklocal identifiers. The reserved field 808 comprises, for example,16-bits. In some embodiments, the reserved field bits are set to zero ontransmission and/or are ignored on receipt. Each of the link identifiers810 comprises, for example, 32-bits to indicate an interface IP addressto identify the incoming or outgoing port corresponding to the link. Theformat of each link identifier 810 should comply with existingLocal/Remote Interface IP Address protocols.

Other enhanced sub-TLVs disclosed herein are for wavelength converterpool information. Because a WSON node may include wavelength converters,at least some embodiments encode structure and properties of a generalwavelength converter pool based on a converter accessibility sub-TLV, awavelength converter range sub-TLV and/or a WC usage state sub-TLV asdescribed herein.

In at least some embodiments, the wavelength converter accessibilityinformation is provided in a sub-TLV of the Node Attribute TLV. Theinformation in the wavelength converter accessibility sub-TLV indicatesthe ability of an ingress port to reach a wavelength converter and of awavelength converter to reach a particular egress port. The length ofthe length converter accessibility sub-TLV corresponds to the length ofthe value field in octets. In at least some embodiments, the wavelengthconverter accessibility sub-TLV occurs at most once within the NodeAttribute TLV.

The wavelength converter range information is also provided in a sub-TLVof the Node Attribute TLV. Because wavelength converters may have alimited input or output range, this range may be specified using one ormore wavelength conversion range sub-TLVs. The length of a wavelengthconverter range sub-TLV corresponds to the length of the value field inoctets. Wavelength converter range sub-TLVs may occur more than oncewithin a given Node Attribute TLV.

The WC usage state information may also be provided as a sub-TLV of aNode Attribute TLV. The WC usage state indicates the usage state ofwavelength converters. The length of the WC usage state sub-TLVcorresponds to the length of the value field in octets. In at least someembodiments, the WC usage state sub-TLV occurs at most once within theNode Attribute TLV.

As disclosed herein, various other sub-TLVs may be added to enhance aLink Set TLV. For example, a WSON Port Wavelength Restrictions sub-TLV,an available wavelengths sub-TLV, and/or a shared backup wavelengthssub-TLV may be added to a Link Set TLV. In WSON networks, generally allthese sub-TLVs above are optional, depending on the implementation. As adefault configuration, there are no restrictions on wavelength, so theWSON Port Wavelength Restrictions sub-TLV may not appear in the LSAs.Meanwhile, in order to be able to compute RWA, an available wavelengthssub-TLV may appear in the LSAs. Even without available wavelengthinformation, path computation may be performed by guessing whatwavelengths may be available (e.g., high blocking probability ordistributed wavelength assignment may be used). The shared backupwavelengths sub-TLV should not appear in the LSAs, if there is nowavelength backup functionality in the WSON networks.

More specifically, the WSON Port Wavelength Restrictions sub-TLVdescribes the wavelength (label) restrictions that the link and variousoptical devices (e.g., OXCs, ROADMs, and waveband multiplexers) mayimpose on a port. These restrictions represent what wavelength may ormay not be used on a link and are relatively static. As an example, if agiven WSON link only supports some specific wavelengths switching, thesewavelength restrictions should be reflected in the routing to beconvenient for wavelength path computation. In WSON networks, thewavelength continuity along the wavelength LSP should be ensured.

FIG. 9 is a schematic diagram of an embodiment of a port wavelengthrestrictions sub-TLV 900. As shown, the port wavelength restrictionssub-TLV 900 comprises a RestrictionKind field 902, a T field 904, areserved field 906 and a MaxNumChannels field 908. The port wavelengthrestrictions sub-TLV 900 also comprises a “wavelength set per action”field 910 that may vary. The reserved field 906 may be reserved forother purposes, and may be set to zero by the sender and ignored by thereceiver. The T field 904 may be a flag used for various purposes. In atleast some embodiments, the RestrictionKind field 902 comprises, forexample, 8 bits to indicate restriction type information. As an example,a RestrictionKind value of 0x01 may indicate simple wavelength selectiverestriction. In such case, the MaxNumChannels (Max number of channels)field 908 indicates the maximum number of wavelengths permitted on theport and the accompanying wavelength set 910 indicates the specificpermitted wavelengths. As another example, a RestrictionKind value of0x02 may indicate a waveband device with a tunable center frequency andpassband. In such case, the MaxNumChannels (Max number of channels)field 908 indicates the maximum width of the waveband in terms of thechannels spacing given in the wavelength set. The correspondingwavelength set 910 is used to indicate the overall tuning range.Specific center frequency tuning information can be obtained fromdynamic channel in use information. The length of the port wavelengthrestrictions sub-TLV 900 corresponds to the length of the value field inoctets. In at least some embodiments, the port wavelength restrictionssub-TLV may occur more than once to specify a complex port constraintwithin the link TLV.

Available wavelengths information also may be provided in a sub-TLV ofthe link TLV. An available wavelengths sub-TLV indicates the wavelengthsavailable for use on the link. Note that there are five approaches for awavelength set which may be used to represent the available wavelengthsinformation. Considering that the continuity of the available orunavailable wavelength set can be scattered for the dynamic wavelengthavailability, there is a burden associated with routing to reorganizethe wavelength set information when the inclusive (or exclusive) list(or range) approaches are used to represent available wavelengthsinformation. Therefore, in some embodiments, only the bitmap set is usedfor representing available wavelengths information.

Various requirements for the global semantics wavelength label and thecorresponding standardized wavelength label are known. Because thewavelength continuity along the wavelength LSP should be ensured withoutwavelength conversion or with partial wavelength conversion, thewavelength availability information (excepting wavelength connectivityinformation) is needed when computing a wavelength LSP. As an example,the wavelength label range [wavelength 1, wavelength 5] of fiber 1 maybe connected to the same wavelength label range of fiber 2. In somecases only wavelength 3 is available to carry the traffic, while otherwavelength labels are occupied. Therefore, in order to compute awavelength path, the available wavelength information needs to be knownby the node performing the computation. If the wavelength availabilityinformation is not known by the node performing the path computation,then the computation can only be performed at the level of TE links. Insuch case, wavelength assignments are resolved locally by the switcheson a hop-by-hop basis enhanced by signaling protocol mechanisms used tonegotiate label selection. However, this scenario may be veryinefficient in the signaling protocol, and can easily lead to blockingproblems where a path is selected for which there is no suitablewavelength availability (unless some or all of the switches along thepath are capable of full wavelength conversion). In the general case oflimited or no wavelength conversion, information on wavelengthavailability enables efficient and accurate path computation.

A standardized label format is described in IETF documentdraft-ietf-ccamp-gmpls-g-694-lambda-labels-04.txt, which is incorporatedherein by reference. If the standardized label format is used directlyto identify the status of every wavelength, the wavelength informationmay be a little more large-scale, because a WSON link often supportsmany wavelengths (e.g., 80 or 160 wavelength systems). To minimize thesize of information, a bitmap wavelength set may be used to indicate thewavelength availability information of a fiber. In such case, only onebit is used to indicate the status of a certain wavelength (thewavelength is either available or not available).

FIG. 10 is a schematic diagram of an embodiment of a wavelengthavailability sub-TLV 1000. The wavelength availability sub-TLV 1000 maycorrespond, for example, to a sub-TLV of a link TLV. The wavelengthavailability sub-TLV 1000 may be used to encode at least one type of theRWA information discussed below when the RWA information is associatedwith at least one node, link, and/or wavelength.

In at least some embodiments, the wavelength availability sub-TLV 1000comprises reserved bits 1002 and a Num Wavelengths field 1004. Thereserved field 1002 may be reserved for other purposes, and may be setto zero by the sender and ignored by the receiver. The Num Wavelengthsfield 1004 comprises, for example, 8 bits to indicate the number ofwavelengths of the link. Further, each bit in the bit map 1018represents a particular frequency with a value of 1/0 indicating whetherthe frequency is available or not. Bit position “0” of the bit map 1018represents the lowest frequency, while each succeeding bit positionrepresents the next frequency above the previous frequency. The channelspacing (CS) between adjacent frequencies is designated by the CS field1010. For example, the CS field 1010 may be set to “1” to indicate achannel spacing of about 12.5 gigahertz (GHz), the CS field 1010 may beset to “2” to indicate a channel spacing of about 25 GHz, or the CSfield 1010 may be set to “3” to indicate a channel spacing of about 50GHz. Further, the CS field 1010 may be set to “4” to indicate a channelspacing of about 100 GHz, or the CS field 1010 may be set to “5” toindicate a channel spacing of about 200 GHz. Further, the S field 1012may comprise about one bit to indicate the sign used to offset from thecenter frequency. For example, the S field 1012 may be set to “0” toindicate a positive (+) sign and may be set to “1” to indicate anegative (−).

Meanwhile, the grid field 1008 may comprise about four bits to indicatethe WDM grid specification being used. For example, the grid field 1008may be set to “1” to indicate an ITU-T DWDM wavelength grid, or the gridfield 1008 may be set to “2” to indicate an ITU-T CWDM wavelength grid.As shown, the wavelength availability sub-TLV 1000 also comprises areserved field 1014 (similar to the aforementioned reserved fields)comprising about eight bits and an “n for lowest channel” field 1016comprising about 16 bits to specify a specific frequency or wavelength.As an example, n may be an integer used to specify a frequency using theformula:

Frequency=193.1 terahertz(THz)±n*(channel spacing)

where the ± is selected based on the sign indicated in the S field 1012and the channel spacing is defined in the CS field 1010.

The values of the bit map 1018 are “1” if available or “0” if assigned(e.g., in use, or failed, or administratively down, or under testing).In accordance with at least some embodiments, the valid length of thebit map 1018 corresponds to Num Wavelengths field 1004 value. However,padded bits 1020 are also to the bit map 1018 so that the number of bitsin the bit map 1018 are aligned with 32-bit fields used for the TLV. Thepadded bits 1020 may be set to 0 and are ignored. Further, bits in thebit map 1018 that do not represent wavelengths (e.g., those in positions(Num Wavelengths−1) and beyond) may be set to zero and are ignored. Thelength of the available wavelengths sub-TLV corresponds to the length ofthe value field in octets. In at least some embodiments, the availablewavelengths sub-TLV 1000 may occur at most once within the link TLV.

In accordance with at least some embodiments, a shared backupwavelengths sub-TLV is provided with a link TLV. The shared backupwavelengths sub-TLV indicates the wavelengths available for sharedbackup use on a link. The length of the shared backup wavelengthssub-TLC corresponds to the length of the value field in octets. In atleast some embodiments, the shared backup wavelengths sub-TLV may occurat most once within the link TLV.

Procedures for routing flooding are also described herein. In accordancewith at least some embodiments, all the sub-TLVs are nested to top-levelTLV(s) and contained in Opaque LSAs. The flooding of Opaque LSAs followpredetermined rules. In the WSON networks, the node information and linkinformation can be classified as two kinds. A first kind is relativelystatic information such as Node ID and Connectivity Matrix information.The other kind is dynamic information such as WC usage state andavailable wavelengths information. In accordance with at least someembodiments, a WSON implementation should take measures to avoidfrequent updates of relatively static information when the relativelystatic information is not changed. Accordingly, a mechanism may beapplied such that static information and dynamic information arecontained in separate Opaque LSAs to avoid unnecessary updates of staticinformation when dynamic information is changed. Further, as with otherTE information, a WSON implementation should take measures to avoidrapid and frequent updates of routing information that could cause therouting network to become swamped. Accordingly, a threshold mechanismmay be applied such that updates are only flooded when a number ofchanges have been made to the wavelength availability information withina specific time. Such mechanisms are configurable if they areimplemented.

In some embodiments, all of the information in the enhanced sub-TLVsdescribed herein may be needed to compute the RWA solution. For example,the SRNG information, connectivity matrix information, wavelengthconverter pool information (e.g., wavelength converter accessibilityinformation, wavelength conversion range information, WC usage stateinformation), WSON port wavelength restrictions information, availablewavelengths information, and shared backup wavelengths informationdisclosed herein may be required for the PCE or control plane controllerto calculate the RWA in the combined RWA architecture described above.However, in other embodiments, only some of the sub-TLV informationdescribed herein may be required to calculate the RWA. For example, thewavelength availability information may not be needed by the PCE orcontrol plane controller in the case of the distributed WA architecture400 described in FIG. 4. Thus, the RWA information that the PCE and/orthe control plane controller needs may vary from case to case.

The network components described above may be implemented on anygeneral-purpose network component, such as a computer or networkcomponent with sufficient processing power, memory resources, andnetwork throughput capability to handle the necessary workload placedupon it. FIG. 11 illustrates a typical, general-purpose networkcomponent suitable for implementing one or more embodiments of thecomponents disclosed herein. The network component 1100 comprises aprocessor 1102 (which may be referred to as a central processor unit orCPU) that is in communication with memory devices including secondarystorage 1104, read only memory (ROM) 1106, random access memory (RAM)1108, input/output (I/O) devices 1110, and network connectivity devices1112. The processor 1102 may be implemented as one or more CPU chips, ormay be part of one or more application specific integrated circuits(ASICs).

The secondary storage 1104 is typically comprised of one or more diskdrives or tape drives and is used for non-volatile storage of data andas an over-flow data storage device if RAM 1108 is not large enough tohold all working data. Secondary storage 1104 may be used to storeprograms that are loaded into RAM 1108 when such programs are selectedfor execution. The ROM 1106 is used to store instructions and perhapsdata that are read during program execution. ROM 1106 is a non-volatilememory device that typically has a small memory capacity relative to thelarger memory capacity of secondary storage 1104. The RAM 1108 is usedto store volatile data and perhaps to store instructions. Access to bothROM 1106 and RAM 1108 is typically faster than to secondary storage1104.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A Generalized Multi-Protocol Label Switching(GMPLS) control plane controller configured to: transmit trafficengineering (TE) properties of GMPLS TE links in an open shortest pathfirst (OSPF) TE link state advertisement (LSA), wherein the TE LSAcomprises a node attribute type-length-value (TLV) including one or moreenhanced sub-TLVs comprising: shared risk node group (SRNG) information,connectivity matrix information, wavelength converter pool information,wavelength switched optical network (WSON) port wavelength restrictionsinformation, available wavelengths information, or shared backupwavelengths information.
 2. The GMPLS control plane controller of claim1, wherein the node attribute TLV comprises a connectivity matrixsub-TLV which represents either a potential connectivity matrix forasymmetric switches or a fixed connectivity for an asymmetric device. 3.The GMPLS control plane controller of claim 2, wherein the connectivitymatrix sub-TLV comprises a connectivity field, a reserved field, linkset A values, and link set B values.
 4. The GMPLS control planecontroller of claim 3, wherein the connectivity field is set to a valueof 0 to indicate the device is fixed or to a value of 1 to indicate thedevice is reconfigurable.
 5. The GMPLS control plane controller of claim2, wherein the connectivity matrix sub-TLV further comprises a link setobject.
 6. The GMPLS control plane controller of claim 5, wherein thelink set object comprises an action field, a directory field, a formatfield, and a plurality of link identifiers.
 7. A GeneralizedMultiprotocol Label Switching (GMPLS) control plane controllerconfigured to: transmit traffic engineering (TE) properties of GMPLS TElinks in an open shortest path first (OSPF) TE link state advertisement(LSA), wherein the TE LSA comprises a link type-length-value (TLV)including one or more enhanced sub-TLVs comprising: shared risk nodegroup (SRNG) information, connectivity matrix information, wavelengthconverter pool information, wavelength switched optical network (WSON)port wavelength restrictions information, available wavelengthsinformation, or shared backup wavelengths information.
 8. The GMPLScontrol plane controller of claim 7, wherein the link TLV comprises aport label restrictions sub-TLV that describes label restrictions that anetwork element and a link may impose on a port.
 9. The GMPLS controlplane controller of claim 8, wherein the port label restrictions sub-TLVcomprises a restriction field that indicates restriction typeinformation.
 10. The GMPLS control plane controller of claim 9, whereinthe restriction field indicates a simple label selective restriction.11. The GMPLS control plane controller of claim 9, wherein therestriction field indicates a label range device with a movable centerlabel and a width.
 12. The GMPLS control plane controller of claim 8,wherein the port label restrictions sub-TLV further comprises a labelset field, and wherein the label set field comprises a label set thatindicates labels permitted on the port.
 13. The GMPLS control planecontroller of claim 12, wherein the port label restrictions sub-TLVfurther comprises a label set field, and wherein the label set fieldindicates an overall label range.
 14. The GMPLS control plane controllerof claim 12, wherein the port label restrictions sub-TLV furthercomprises a field that indicates a maximum range of labels permitted onthe port.